This is a dose escalation and dose expansion study to compare how well BGB-43395, a selective cyclin-dependent kinase 4 (CDK4) inhibitor, works as monotherapy or in combination with fulvestrant, letrozole, or elacestrant in participants with hormone receptor positive (HR+) and human epidermal growth factor 2 negative (HER2-) breast cancer (BC) and other advanced solid tumors. The main purpose of this study is to explore the recommended dosing for BGB-43395.
| Study Arm | Population | Intervention | Comparison | Outcome |
|---|---|---|---|---|
Phase 1a: Dose Escalation + Safety Expansion |
Advanced solid tumors with CDK4 dependency |
Part A: BGB-43395 monotherapy in advanced solid tumors with CDK4 dependency Part B: BGB-43395 + fulvestrant in 2L+ HR+/HER2- BC, OC, EC Part C: BGB-43395 + letrozole in 2L+ HR+/HER2- BC, OC, EC |
None |
Primary Endpoints: Safety and tolerability, MTD and RDFE Secondary Endpoints: ORR, DoR, TTR, and PK |
Phase 1b: Dose Expansion |
1L HR+/HER2- CDK4/6 inhibitor naïve BC or 2L+ HR+/HER2- CDK4/6 inhibitor progressed BC |
BGB-43395 + fulvestrant (2L+ HR+/HER2- CDK4/6 inhibitor progressed BC) BGB-43395 + letrozole (1L HR+/HER2- CDK4/6 inhibitor naïve BC) |
None |
Primary Endpoints: ORR Secondary Endpoints: DoR, TTR, DCR, CBR, PFS, safety, PK |
